Synthesis 2017; 49(07): 1613-1622
DOI: 10.1055/s-0036-1588107
paper
© Georg Thieme Verlag Stuttgart · New York

Towards a Series of Chiral Primary Amines Bearing α-Amino Acid and Benzo[d]imidazole Pendants, and Their Application in Asymmetric Aldol Reactions

Pravinkumar Hansraj Mohite, Pavel Drabina, Filip Bureš*
  • Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 53210, Czech Republic   Email: filip.bures@upce.cz
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Publication History

Received: 03 October 2016

Accepted after revision: 02 November 2016

Publication Date:
08 December 2016 (eFirst)

Abstract

A straightforward reaction path towards chiral primary amines bearing α-amino acid and benzo[d]imidazole pendants has been developed. Six starting essential α-amino acids were converted into the target chiral amines in a four-step synthesis. The prepared amines were screened as organocatalysts in the direct asymmetric aldol reaction between 4-nitrobenzaldehyde or isatin and acetone or cyclohexanone. The aldol adducts were obtained in good chemical yields, diastereoselectivity­ up to 97:3 (reactions with cyclohexanone), and enantioselectivity up to 71% ee. Trifluoroacetic acid and benzoic acid proved to be the best cocatalysts for the aldol process on 4-nitrobenzaldehyde and isatin, respectively.

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